Meta-phenylenediamine, a useful chemical intermediate, has been prepared by the catalytic reduction of m-dinitrobenzene. Dinitration of benzene is difficult because the ring is deactivated and product separation is difficult, thus rendering the dinitrobenzene feedstock for m-phenylenediamine (M-PDA) synthesis very expensive. U.S. Pat. No. 4,387,247 discloses the reduction of di- or polynitro aromatic compounds by gaseous H.sub.2 S over a solid catalyst. CO gas is added to promote formation of amino groups from all nitro groups in the molecule. The disproportionation of toluenediamine (TDA) to m-PDA was reported as a secondary reaction under the CO/H.sub.2 S atmosphere.
U.S. Pat. No. 4,405,812 discloses a process for the ortho dealkylation of aromatic amines by contacting o-methyl substituted aromatic amines with a nickel catalyst at about 200.degree.-400.degree. C. The demethylation of dimethylanilines over nickel catalysts resulted in poor selectivity to the dealkylation product, toluidine when run under conditions similar to those used in aromatic hydrocarbon disproportionation.
U.S. Pat. No. 3,123,644 discloses a process for dealkylating a nuclear polyalkyl primary aromatic amine having a tertiary alkyl group of 4 or 5 carbon atoms on at least one ring carbon atom in the ortho-position with respect to the amino group. The polyalkyl primary aromatic amine is converted into a mono-nuclear primary aromatic amine by heating at a temperature in the range of 150.degree.-350.degree. C. under superatmospheric pressure with an acceptor aromatic amine and in the presence of a finely divided silica-alumina type catalyst.
U.K. patent application No. 810,751 discloses a process for the dealkylation of aromatic hydrocarbons. The process is carried out at a temperature from 450.degree. to 700.degree. C. and H.sub.2 pressure above 40 atmospheres in the presence of a catalyst comprising active carbon by itself or with a small amount of metallic activator.